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Making a FITS tape

  So now that you have some data, you probably want to save it to tape. At each telescope there are both Exabyte and DAT tape drives; there are also a few 9-track dinosaurs still roaming some of the domes. Since all of our ICE systems subscribe to IRAF networking, and you can in fact use any tape drive in any dome, although you need to check with the appropriate astronomer if you want to use someone else's tape drive---be nice!

The first step is to allocate the appropriate tape drive. The 1600/6250 bpi drives are known as mta to IRAF; the Exabytes are known as mtb; and the DAT drives are known as mtc. (You can find these names printed on each drive unit; you can also run the command devices to list both the IRAF and Unix names of all the I/O devices on the mountain.) Thus you need to do an

allocate mta

to allocate the 1600/6250 bpi tape drive at your telescope; to allocate a drive elsewhere you might do something like a

allocate lapis!mta

The parameters for wfits are shown in Figure 7.

The crucial parameters are:

In order to check to see what is on the tape, you can list the titles quite easily. Simply do a

rfits mtb 1-999 make-- short+ old+

to see what's there. To direct this output into a file, you can add a > tapelist to the end, and then you can print that list on the lineprinter by a simple lprint tapelist. Alternatively, you could choose to read a single file back onto disk to examine:

rfits mtb 15 junk make+ old+

will create an image with the original name. (Note that even if you specify old+ you must still give the name of a legal temporary file in the output file position, i.e. junk in this example.) If the same image name already exists on disk, you should instead use old- to create an image named junk, or whatever you wish.

As you write your tape, you will get a file-by-file account of what is going on the tape. When you come to the end of the tape, you will find that there is a message saying that the file was NOT completely written to tape. An easy way to continue at this point is to edit your ``at" file to remove the names of the files that were successfully written to tape. Rewind the tape with rew mtb, mount the new tape, and then re-run wfits, remembering to set newtape=yes.

The new ``x" IRAF tool ``xtapemon" will allow you to see how much space is left on your tape, and to keep tabs on where on the tape you are; see Sec. A.2.

NOTE: If you do write additional files to an ``old tape" (one containing useful data but which had previously been removed from the drive), make certain that the software (IRAF and Unix) is aware that the tape has been rewound before starting to write to the tape----or your old data may be overwritten! To safeguard against this possibility we suggest that you ALWAYS swap tapes by first:


next previous contents
Next: Safe Taping Previous: Writing Your Data To Tape
Updated: 26Aug1996